The red blood cell, also called the erythrocyte cell, is biconcave, in the shape of a crushed disc, and formed in the bone marrow
. The red blood cells
, the pigment that gives it its red color. Its primary function is to transport oxygen in the blood. Composed of protein and iron, hemoglobin allows the cell to bind oxygen and bring it to the body cells for their operation. The life of a red blood cell is 120 days on average.